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Aljoharah Alkanaan, Omar Kirat, Robert Barsotti, Turki Almubrad, Adnan Khan, Saeed Akhtar; Ultrastructural Study of lamellar organization of Peripheral and Central Stroma of Keratoconus Cornea. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2895.
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© ARVO (1962-2015); The Authors (2016-present)
Keratoconus (KC) is a progressive bilateral asymmetrical corneal disorder characterized by localized corneal thinning and conical protrusion, leading to high myopia, irregular astigmatism, corneal scarring and visual impairment. In this study we assess the lamellar organization of the peripheral and central stroma of the KC and normal cornea.
Three normal and three keratoconus corneas were fixed in 2.5% glutaraldehyde and post fixed in the osmium tetroxide. The tissue were dehydrated in a graded series of ethanol and processed for electron microscopy. The Ultrathin sections were observed under JOEL 1400 TEM and digital images were taken with a bottom mounted 11 megapixel Quamisa camera, using iTEM software. Measurement of lamellae were carried out with iTEM software. Statistics were performed using the SPSS programme.
In the central part of the KC cornea, undulation of the lamellae was observed in the anterior, middle and posterior stroma whereas in the peripheral part, the undulation was observed in middle and the posterior stroma. Collagen fibrils were disorganized and of variable size in the undulating lamellae. Electron dense granular material was present among the collagen fibrils.Mean lamellar thickness of the peripheral (752.79±31.98nm) and central (828.76±25.75nm) stroma of KC cornea was significantly (P〈 0.001) thinner than the peripheral (1928.90±108.13nm) and central (1330.10±85.07 nm) stroma of the normal cornea. Among the KC cornea, the mean lamellar thickness of the peripheral middle (1030.32±86.25nm) and posterior (615.68±30.94nm) stroma were also significantly (P〈0.05) different from the central middle (1151.1±65.48nm) and posterior 783.57±31.10nm) stroma. However the mean lamellar thickness of the anterior stroma did not differ significantly between the periphery (686.84±46.47nm) and center (600.84±25.10 nm) of KC cornea (P=0.558).In both the normal and KC cornea, the number of lamellae in the central stroma (296,241) was consistently less than that in the peripheral stroma (360 in both normal and KC corneas).
The results of this study shows that KC pathological changes to the lamellar organization is not limited to the central stroma but rather extends to affect the lamellae within the peripheral stroma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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